The water-cement ratio is a key factor in determining the strength and durability of concrete. It refers to the ratio of the mass of water to the mass of cement used in a concrete mix. A lower water-cement ratio typically results in stronger concrete, while a higher ratio can lead to weaker concrete with increased porosity. Maintaining the right water-cement ratio is crucial for achieving the desired properties of concrete. It affects not only the strength but also the workability and setting time. Properly managing this ratio helps ensure that the concrete performs well in various applications, from buildings to roads.